Vertex Array Object

I've just started out with OpenGL I still haven't really understood what Vertex Array Objects are and how they can be employed.
If Vertex Buffer Object are used to store vertex data (such as their positions and texture coordinates) and the VAOs only contain status flags, where can they be used? What's their purpose?
As far as I understood from the (very incomplete and unclear) GL Wiki, VAOs are used to set the flags/statūs for every vertex, following the order described in the Element Array Buffer, but the wiki was really ambiguous about it and I'm not really sure about what VAOs really do and how I could employ them.

VAOs are useful, because you don't have to set up everytime all attributes. It should also be faster just bind one VAO rather then setting all attributes.
 
 

// BEGIN INITIALIZATION

// Define some vertex data

struct Vertex {
  GLfloat position[3];
  GLfloat texcoord[2];
};
Vertex vertexdata[NUM_VERTS] = { ... };
GLubyte indexdata[NUM_INDICES] = { 0, 1, 2, ... };

// Create and bind a VAO

GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);

// Create and bind a BO for vertex data

GLuint vbuffer;
glGenBuffers(1, &vbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vbuffer);

// copy data into the buffer object

glBufferData(GL_ARRAY_BUFFER, NUM_VERTS * sizeof(Vertex), vertexdata, GL_STATIC_DRAW);

// set up vertex attributes

glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, position));
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, texcoord));

// Create and bind a BO for index data

GLuint ibuffer;
glGenBuffers(1, &ibuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibuffer);

// copy data into the buffer object

glBufferData(GL_ELEMENT_ARRAY_BUFFER, NUM_INDICES * sizeof(GLubyte), indexdata, GL_STATIC_DRAW);

// At this point the VAO is set up with two vertex attributes

// referencing the same buffer object, and another buffer object

// as source for index data. We can now unbind the VAO, go do

// something else, and bind it again later when we want to render

// with it.


glBindVertexArray(0);

// END INITIALIZATION


// BEGIN RENDER LOOP


// This is it. Binding the VAO again restores all buffer

// bindings and attribute settings that were previously set up

glBindVertexArray(vao);
glDrawElements(GL_TRIANGLES, NUM_INDICES, GL_UNSIGNED_BYTE, (void*)0);

// END RENDER LOOP